(i) Field of the Invention
The present invention relates to a photoelectric converter that is capable of conversion between light and electricity. Further, the present invention relates to a photoelectric composite connector and a substrate that can be used in such a photoelectric converter, i.e. a photoelectric composite connector using an electrical connector structure and a substrate using the photoelectric composite connector.
(ii) Description of the Related Art
A photoelectric converter has been widely used in such a manner that it is connected to optical transmission means such as an optical fiber so as to, for example, transmit a high-frequency electrical signal. As is well known, the high-frequency electrical signal may have noise when the traveling distance is long. Thus, it is often practiced that an optical signal is used in place of the electrical signal and a photoelectric converter is used at the end of transmission so as to convert the optical signal into the electrical signal or the electrical signal into the optical signal and use the electrical (or optical) signal.
In recent years, an attempt to use such an optical signal in short-distance connection, e.g. on a substrate (between devices on the same substrate) or between substrates, by use of a small-sized photoelectric converter in particular has started. Illustrative examples of currently usable devices include a type having an optical waveguide embedded in a substrate and a type having a film waveguide laminated on a substrate. In the case of these types, an optical signal is transmitted through a waveguide provided inside or outside a substrate, and the optical signal is converted into an electrical signal by a photoelectric conversion device which is provided separately from the above waveguide. In addition to these types, another type has an optical member at the tip of an optical fiber as a plug-side connector and uses a photoelectric conversion device as the corresponding receptacle-side connector to perform conversion between light and electricity. However, these devices require a highly accurate optical alignment between the optical member or waveguide and the photoelectric conversion device and also require a highly accurate alignment between the optical member and the substrate when the optical member is soldered to the substrate. In particular, since the substrate hardly enjoys surface dimensional accuracy due to warpage or distortion, it is difficult to control such an alignment. Further, although these devices require a measure for dealing with degradation of the performance of light-emitting and light-receiving elements mounted in the devices, e.g. a measure for static electricity, it is difficult to take a measurement for the performance degradation since the light-emitting and light-receiving elements must be mounted on the substrate having a number of other electrical elements mounted thereon.
With respect to an optical alignment, a technique for facilitating an optical alignment between an optical fiber and a waveguide is disclosed in Japanese Patent Laid-Open Publication No. 264587/2001 and other literatures. The literature discloses a structure having an optical connector section, more specifically, a structure which enables an optical fiber to be connected to an optical connector section integrated with a waveguide having a photoelectric conversion device by means of an atonality core. However, the connector section used in this structure is a so-called optical connector section which is merely used for optical connection and is not used for electrical connection.
Further, with respect to a photoelectric converter, a photoelectric converter having an integrated module, i.e. a module comprising integration of waveguide (light path right-angle conversion waveguide) and a photoelectric conversion device, at the tip of an optical fiber has been presented in the fourth Electronic System Integration Study Debriefing Session taken place in the National Museum of Emerging Science and Innovation at Jun. 13, 2003 under the auspices of Technology Research Association—Association of Super-Advanced Electronics Technologies (ASET) and others. The integrated module presented in the session is considered to be an effective constitution which facilitates an optical alignment between a waveguide and a photoelectric conversion module. However, a problem of alignment between a device and a substrate still remains even in such a constitution.    Patent Literature 1: Japanese Patent Laid-Open Publication No. 264587/2001    Non-Patent Literature 1: Fourth Electronic System Integration Study Debriefing Session, (time) Jun. 13, 2003, (place) National Museum of Emerging Science, (host) Technology Research Association—Association of Super-Advanced Electronics Technologies (ASET), (co-host) National Institute of Advanced Industrial Science and Technology (AIST), (sponsorship) New Energy and Industrial Technology Development Organization (NEDO)
The present invention has been conceived to solve these problems of the prior art. An object of the present invention is to provide a photoelectric composite connector that allows an accurate and easy optical alignment between a photoelectric conversion device and a waveguide and does not require as high accuracy in alignment between an optical member and a substrate as an optical connector does, and a substrate using the photoelectric composite connector. Another object of the present invention is to makes it possible to connect or disconnect a substrate by a connector and improve usability.